According to docs printing queries is as simple as print(query).
But according to update function description, it returns an integer
:return: the count of rows matched as returned by the database's
"row count" feature.
My code:
state = 'router_in_use'
q = self.db_session.query(Router).filter(
Router.id == self.router_id,
).update(
{Router.state: state}, synchronize_session=False
)
#print(q) outputs just 1
self.db_session.commit()
Is there a way to print q query in SQL language?
Query itself works fine.
python 3.8
Related
I am using the peewee ORM for a python application and I am trying to write code to fetch batches of records from a SQLite database. I have a subquery that seems to work by itself but when added to an update query the fn.EXISTS(sub_query) seems to have no effect as every record in the database is updated.
Note: I am using the APSW extension for peewee.
def batch_logic(self, id_1, path_1, batch_size=1000, **kwargs):
sub_query = (self.select(ModelClass.granule_id).distinct().where(
(ModelClass.status == 'old_status') &
(ModelClass.collection_id == collection_id) &
(ModelClass.name.contains(provider_path))
).order_by(ModelClass.discovered_date.asc()).limit(batch_size)).limit(batch_size))
print(f'len(sub_query): {len(sub_query)}')
fb_st_2 = time.time()
updated_records= list(
(self.update(status='new_status').where(fn.EXISTS(sub_query)).returning(ModelClass))
)
print(f'update {len(updated_records)}: {time.time() - fb_st_2}')
db.close()
return updated_records
Below is output from testing locally:
id_1: id_1_1676475997_PQXYEQGJWR
len(sub_query): 2
update 20000: 1.0583274364471436
fetch_batch 20000: 1.1167597770690918
count_things 0: 0.02147078514099121
processed_things: 20000
The subquery is correctly returning 2 but the update query where(fn.EXISTS(sub_query)) seems to be ignored. Have I made a mistake in my understanding of how this works?
Edit 1: I believe GROUP BY is needed as rows can have the same granule_id and I need to fetch rows up to batch_size granule_ids
I think your use of UPDATE...WHERE EXISTS is incorrect or inappropriate here. This may work better for you:
# Unsure why you have a GROUP BY with no aggregation, that seems
# incorrect possibly, so I've removed it.
sub_query = (self.select(ModelClass.id)
.where(
(ModelClass.status == 'old_status') &
(ModelClass.collection_id == id_1) &
(ModelClass.name.contains(path_1)))
.order_by(ModelClass.discovered_date.asc())
.limit(batch_size))
update = (self.update(status='new_status')
.where(self.id.in_(sub_query))
.returning(ModelClass))
cursor = update.execute() # It's good to explicitly execute().
updated_records = list(cursor)
The key idea, at any rate, is I'm correlating the update with the subquery.
I am trying to run a system SP (which is a pre-built) using python pyodbc. In fact I am trying to see the dependencies on a table using sp_depends '<Object name>';
I am using the below code snippet.
df_f=[]
l_table = ['table_1','table_2','table_3']
try:
for l in l_table:
sql = """EXEC sp_depends '{0}';""".format(l)
while cur.nextset():
cur.execute(sql)
c = cur.fetchall()
df_l= pd.DataFrame.from_records(c, columns = [desc[0] for desc in cur.description])
df_l['Referenced_Object'] = l
df_f.append(df_l)
break
except pyodbc.Error as err:
s = str(err)
print(s)
finally:
cur.close()
cnxn.close()
The above code is not running. It is not throwing error but not appending anything in df_f.
If I run the above SP separately, I am getting the below error:
ProgrammingError: No results. Previous SQL was not a query.
I have taken help from this SO thread.
I am not able to SET NOCOUNT ON in this SP as this is a built-in and therefore I am not able to get the desired information in dataframe.
Any clue on this?
As I mentioned in the comments, sp_depends has been deprecated; it should not be used. As per the documentation you should be using sys.dm_sql_referencing_entities and sys.dm_sql_referenced_entities instead.
You can get similar results to the sp_depends with the following queries. You would need to replace the variables with parameters from your programming language (not inject them):
SELECT CONCAT(re.referenced_schema_name,'.', re.referenced_entity_name) AS [name],
o.type_desc AS [Type],
CASE re.is_updated WHEN 0 THEN 'no' WHEN 1 THEN 'yes' END AS updated,
CASE re.is_selected WHEN 0 THEN 'no' WHEN 1 THEN 'yes' END AS selected,
re.referenced_minor_name AS [column]
FROM sys.dm_sql_referenced_entities(QUOTENAME(#SchemaName) + N'.' + QUOTENAME(#ObjectName) ,'OBJECT') re
JOIN sys.objects o ON re.referenced_id = o.object_id;
SELECT DISTINCT
CONCAT(re.referencing_schema_name,'.', re.referencing_entity_name) AS [name],
o.type_desc AS [Type]
FROM sys.dm_sql_referencing_entities(QUOTENAME(#SchemaName) + N'.' + QUOTENAME(#ObjectName) ,'OBJECT') re
JOIN sys.objects o ON re.referencing_id = o.object_id;
I would like get a list of values from a DB table in python using cx_oracle. I am unable to write a query with two where conditions one of single value and another of a list.
I am able to achieve it when I filter it two strings separately or only filter it by a list of string. But could not achieve it together!!
output_list=[]
catlist = ','.join(":x%d" % i for i, _ in enumerate(category_list))
db_cursor = connection.cursor()
db_cursor.execute("""
SELECT LWEX_WORD_EXCLUDE
FROM WCG_SRC_WORD_EXCLUDE
WHERE LWEX_CATEGORY IN (%s) and LWIN_USER_UPDATED = :did""" % catlist, category_list, did =argUser)
for word in db_cursor :
output_list.append(word[0])
The current code throws an error. But if I have either of the conditions separately then it works fine. The python version that I am using is 3.5
You cannot mix and match "bind by position" and "bind by name", which is what you are doing in the above code. My suggestion would be to do something like this instead:
output_list=[]
catlist = ','.join(":x%d" % i for i, _ in enumerate(category_list))
bindvals = category_list + [arguser]
db_cursor = connection.cursor()
db_cursor.execute("""
SELECT LWEX_WORD_EXCLUDE
FROM WCG_SRC_WORD_EXCLUDE
WHERE LWEX_CATEGORY IN (%s) and LWIN_USER_UPDATED = :did""" % catlist, bindvals)
for word in db_cursor :
output_list.append(word[0])
Let's suppose I have the following table :
Id (int, Primary Key) | Value (varchar)
----------------------+----------------
1 | toto
2 | foo
3 | bar
I would like to know if giving two request, the result of the first must be contained in the result of the second without executing them.
Some examples :
# Obvious example
query_1 = "SELECT * FROM example;"
query_2 = "SELECT * FROM example WHERE id = 1;"
is_sub_part_of(query_2, query_1) # True
# An example we can't know before executing the two requests
query_1 = "SELECT * FROM example WHERE id < 2;"
query_2 = "SELECT * FROM example WHERE value = 'toto' or value = 'foo';"
is_sub_part_of(query_2, query_1) # False
# An example we can know before executing the two requests
query_1 = "SELECT * FROM example WHERE id < 2 OR value = 'bar';"
query_2 = "SELECT * FROM example WHERE id < 2 AND value = 'bar';"
is_sub_part_of(query_2, query_1) # True
# An example about columns
query_1 = "SELECT * FROM example;"
query_2 = "SELECT id FROM example;"
is_sub_part_of(query_2, query_1) # True
Do you know if there's a module in Python that is able to do that, or if it's even possible to do ?
Interesting problem. I don't know of any library that will do this for you. My thoughts:
Parse the SQL, see this for example.
Define which filtering operations can be added to a query that can only result in the same or a narrower result set. "AND x" can always be added, I think, without losing the property of being a subset. "OR x" can not. Anything else you can do to the query? For example "SELECT *", vs "SELECT x", vs "SELECT x, y".
Except for that, I can only say it's an interesting idea. You might get some more input on DBA. Is this an idea you're researching or is it related to a real-world problem you are solving, like optimizing a DB query? Maybe your question could be updated with information about this, since this is not a common way to optimize queries (unless you're working on the DB engine itself, I guess).
I have the following code in python. I get this error ->tuple indices must be integers, not str
How can I pass these values into the query? I have other examples where this approach works perfectly, i don't understand why it's failling here.
def request_events_json(uei,interval,conn):
cur = conn.cursor()
events_query ="""select e.nodeid,n.nodelabel,e.ipaddr,count(*) as total,min(e.eventcreatetime),max(e.eventcreatetime),(regexp_matches (e.eventlogmsg,E': %(.*)'))[1] as msglog
from events e, node n where e.eventuei = (%s) and e.eventcreatetime > now() - interval (%s) and n.nodeid=e.nodeid
group by n.nodelabel,e.nodeid,e.ipaddr,msglog
order by e.nodeid, count(*) desc limit 10;"""
try:
print('## Requesting events ##')
cur.execute(events_query,('uei.opennms.org/syslogd/cisco/line','5 min'))
.......
With my version of PostgreSQL the round brackets after interval are forbidden.
Update:
It is the percent-sign in the regexp. Double it.